Following on from the introduction of DFM Xpress for SolidWorks 2008, Geometric (GSSL) has just released a fully fledged version of the manufacturability analysis utility. Al Dean takes a look.

There are many types of analysis and simulation within the 3D modelling world. There are solutions for fluid flow, structural integrity, heat transfer and radiation, kinematics - the list goes on. But one area seems to be overlooked, and happens to be one of the most critical when it comes to realising a product - manufacturability. In these days, where the emphasis on compressing the development cycle has never been greater, this strikes me as a bit odd. The good news is that Geometric has introduced its DFM family of products, which provide a series of checks to help ensure that your parts can be manufactured and, more specifically, machined, either by milling, turning or the increasingly popular mill/turn.

DFM pro includes a wide variety of checks for manufacturability on milled parts. Here the system has identified Deep Holes, where the depth to diameter ratio has been exceeded.

There are three levels of product available. The first is the free utility integrated into SolidWorks 2008, DFM Xpress. Next up is the 'pay for' version, DFM Pro, which provides much more complete functionality. The final option is DFM Enterprise, which sees the DFM Pro tools integrated into a fully customisable environment. So let's start with a look at what's in SolidWorks 2008 with DFM Xpress.

DFM Xpress

As with all Xpress utilities within SolidWorks, the DFM Xpress add-on is free for everyone. As such, it's a taste of the 'paid for' products - a sales tool, some might say. You can perform some checks to ensure that your component can be machined or turned. You start with the part in question, load up the add-in, and define the part type. DFM Xpress then divides its checks into Prismatic or Turned parts. For Prismatic parts, the basic checks are feature accessibility (these are geared towards basic 3-axis milling), fillets (not on outer edges but present within internal features), and hole/cavity intersections. There are also checks that can be tailored towards your requirements, such as hole depth to diameter ratio, pocket depth, flat bottomed holes, whether the holes conform to standard drill sizes, or if the hole entry is perpendicular to the surface. There are also a number of adaptable tolerance checks for minimum angular and linear tolerance zones. These same checks are used for turned parts, but with the addition of corner radii and percentage bore relief.

One thing that is important to note is that the DFM tools, irrespective of which variant you're using, work just as well with imported or third-party geometry. The system uses GSSL's own feature recognition technology (as found in FeatureWorks incidently) and not the SolidWorks feature geometry from the SolidWorks part file. This means that you can run the same checks and maintain the same IP across all of your data, irrespective of your geometry source.

To set the system going you hit run and it presents you with the results, dividing them between those checks that passed and failed. Each check can be expanded and you can see exactly where and why the problem occurred, with text feedback and a highlight on the model.

DFM Pro

DFM Pro offers the same set of rules, checks and other validation analyses as the Xpress version, but moves it up to a higher level. This is done on several fronts. Firstly, the Pro variant has more checks that cover not only milled and turned parts, but also sheet metal parts. Secondly, customisation and standardisation are key. The Pro version adds the ability to fully customise each rule within a database and you can also have multiple databases.

The sheet metal checks look for problems associated with manufacturing sheet forms, such as the shown error, where a hole is placed too close to a bend.

Alongside the variation of values and parameters to tailor each check to your requirements, you can also assign an importance value. This means that once you have a result from the analysis, you can clearly and quickly see where the critical problems are, work on them and then work through the rest. But let's look at how this affects the workflow. You follow the same workflow, load the part, load the set of checks you want to use, then have the system chunk through the feature recognition and processing to inspect the part. You are then presented with a list of checks. You're immediately shown the rules that have failed (flagged in red), checks that have passed and those that aren't applicable.

The most important are those that have failed and you can further organise these by filtering the results by importance, so critical problems can be dealt with immediately. Again, feedback is linked, so selecting the check instance will highlight the geometry that it's referring to on screen. The system also gives you a tooltip to show the details of that failure. While this interactive result inspection process is useful, what you really need to be able to do is formalise those results into a report. This is generated automatically in an XML format and provides details on each failure including images for each. Then if you're working in a managed environment, it can be attached to a revision of a part, and passed around with ECO workflows to ensure that everyone involved can gain an understanding of both why the part failed the checks and what needs to be done to fix the problem.

The sheet metal checks work slightly differently, as they are inspecting different manufacturability concerns. To start a sheet metal part inspection you need to define the database of rules as normal, but also a datum face, from which the part is unfolded. It will also check material libraries and bend radii to ensure that the part you're manufacturing can be built using the materials that you keep in stock if required.